Drug absorbefacients are generally added to medicines that contain pharmacologically active substances to improve absorption of the pharmacologically active substances (see, for example, Crit. Rev. Ther. Drug Carrier Syst., S. Muranishi, 7, p1–33 (1990), etc.).
However, medicines that contain pharmacologically active substances and drug absorbefacients have a side effect, i.e., damaging the intestinal mucosa of the small intestine, large intestine, rectum, etc. (see, for example, E. S. Swenson, W. B. Milisen, W. Curatolo, Pharm. Res., 11(8), p1132–1142 (1994), etc.). Such side effect is attributable to the drug absorbefacient.
To reduce the occurrence of this side effect, the amount of the drug absorbefacient has to be as small as possible. However, when the amount of drug absorbefacient is reduced, it renders a problem that its effect in promoting absorption of the pharmacologically active substance becomes weaker.
To attempt to overcome this drawback, arginine and like amino acids have been added to medicinal compositions that contain pharmacologically active substances and drug absorbefacients (see Y. Kinouchi, N. Yata, Biol. Pharm. Bull., 19(3), p375–378 (1996)).
Addition of amino acids can prevent damage of the intestinal mucosa to some degree; however, its effect is unsatisfactory. Therefore, development of medicinal compositions that can further suppress damage of the intestinal mucosa is demanded.
It is known that polyamines have an effect in promoting maturation of the digestive tracts of infants (Japanese Unexamined Patent Publication No. 1998-262607) and that polyamines have an effect in protecting the gastric mucous membrane by preventing secretion of gastric acid (Japanese Unexamined Patent Publication No. 1983-131914). However, the above-mentioned publications nowhere teach nor suggest that polyamines improve the absorption of low molecular weight pharmacologically active substances having a molecular weight of about 1000 or less. Furthermore, no case to date has been reported that polyamines were used to improve the absorption of pharmacologically active substances in the intestinal tract.